The present invention relates to a hydraulic type vehicle height adjusting device for a vehicle shock absorber.
Such a kind of hydraulic type vehicle height adjusting device is publicly known for example from U.S. Patent No. 4,159,105. FIGS. 10 and 11 are schematic views of the shock absorber having the vehicle height adjusting device in the above mentioned prior art. In the drawings, reference character 1 designates a damper cylinder, 2 a piston, 3 a piston rod, 4 a suspension spring, 5 a rebound spring, 6 a stopper rubber, and 7 a member which is connected to the piston rod 3 and formed with a vehicle height adjusting cylinder 11 at the peripheral portion thereof. Reference character 8 designates a mounting member for attaching the shock absorber to the body of a motorcycle, 9 a mounting member for attaching the shock absorber to the axle of the motorcycle, and 10 a vehicle height adjusting piston which supports one end of the suspension spring 4 and which is slidably moved up and down within the vehicle height adjusting cylinder. FIG. 10 illustrates the shock absorber for the motorcycle with a weight of a rider thereon which is not adjusted in vehicle height and this normal vehicle height is advantageously used for driving the motorcycle on the streets. FIG. 11 shows a position where adjustment in vehicle height is made to drive the motorcycle on a waste land from the position shown in FIG. 10. That is, when the vehicle height adjusting cylinder 11 formed in the peripheral portion of the member 7 is supplied with hydraulic fluid, the vehicle height adjusting piston 10 is displaced upwardly and the initial preset load of the suspension spring becomes greater, but since the live load remains unchanged, the load applied to the suspension spring is same as the load before increase in vehicle height. Accordingly, the piston rod 3 is drawn out from the damper cylinder 1 by the amount of displacement of the vehicle height adjusting piston 10 so that the vehicle height increases from L.sub.1 to L.sub.2. This increases the initial preset load of the suspension spring with the result that the spring load after increase in vehicle height per the amount of the same stroke becomes greater and this gives the motorcycle rider a rigid ride. Further, since the total stroke lt of the shock absorber remains unchanged after increase in vehicle height, even if increase in vehicle height is performed when the motorcycle has entered into a waste land, the shock absorber can not absorb any greater shock.